The present invention is directed to push to close latches, and specifically a release mechanism for opening the push to close latch.
Push to close latches typically, have a tapered, ramp-ended, blade-shaped pawls or bar-shaped pawls. These pawls are spring-biased to the latched/closed position, wherein the pawl extends outwardly from the latch housing. As the pawl of a push to close latch encounters the striker, the ramping force pushes the pawl inward against the spring force until the pawl clears the striker, wherein after the spring then forces the pawl to its extended position and the latch becomes latched.
A lock plug with a pivoting blade striker can be incorporated to provide both the striker and a key lock function, wherein the push to close latch is in a separate housing. When a passive striker is used, a retraction knob may be incorporated into the pawl housing to retract the pawl against its outwardly biasing spring. A lock plug can be used instead of the retraction knob, wherein as the key turns the plug a linkage retracts the pawl into the housing.
Alternately, paddles have been used instead of knobs or lock plugs to activate the pawl to retract it against the force of its biasing spring and into the housing.
With the advent of more security systems, it has become desirable to utilize push to close latches, which are thereby locked when latched. With such security push to close latches it has also become desirable to active, i.e., to operate the latch remotely. Such remotely operated, push to close latches are electrically operated, and therefore are electromechanical devices. The remote activation can be by the operation of an electric signal button operated by a guard or a security officer, or by an electric signal button operated by a resident of an apartment in an apartment building, or by a signal generated by a code entry pad or swipe card reader. The electric signal causes the pawl to be retracted so that the door may be opened.
Typically, the activation device at the latch is an electromagnet or a solenoid. When the electric current flows, the pawl is retracted into the housing and the door can open. When the electric current stops the biasing spring forces the pawl to the extended position.
These electrically operated, prior electromechanical push to close latches have developed problems because of wear and erratic operation, and because of the timing and length of the electric activation signal when the button operator is out of sight of the door and the latch being operated. As an example, if the door is pulled prior to the pawl being retracted, the pawl can bind and the solenoid activator is unable to retract the pawl. Various installations limit the size of the latch housing and therefore the capacity and strength of electromagnetic activator or the solenoid.
What is desired is a latch which is smoothly operating and which has a controlled operation for pawl movement.
What is further desired is a latch which is easily reconfigured for a plurality of different installations.